I installed an 5inch monster rpm tach in my 95 civic ej in 08. For about the past 8mos it hasnt worked right. It jumps all over the place. Even when its ideling it‘ll jump. Ive checked all the wire contections and they all seems good. (although my car has started to putt the last few mos ago. Like ive stated in another post. I beleive the putt is ignition related. When you give it gas, it‘ll start crackeling and sound like its missing. It has new injectors, fuel, and injector cleaner in it, new plugs & wires. Im thinking I should just through a whole new distributor on it with all new cores. But thats kinda priceyy$$$... But, im thinking its something to do with it.)

 

have you checked the distributor cap for it fouling up? "white **** all over the inside contacts" also take the ignition coil and ignition control module to autozone and have them test it. take off the distributor cap, theirs 2 screws holding the ignition coil in, remove those 2 along with the wires "take pictures so you know where everything goes or draw a diagram" then the ignition control module, grey 4 pin module bolted with 2 screws on the lip of the distributor. take that out as well too and have it tested also. only other thing i can think of is your timing is off. or you hooked up the tach to something wrong